Field of the Invention
The invention relates to an electrical component comprising an electric circuit element encapsulated in an electrically insulating material which secures the circuit element in a housing which is open on one side, said circuit element having two external mutually parallel leads which are parallel to the end faces of the circuit element.
Description of the Prior Art
Electric circuit elements in the meaning of the invention are in the first instance electrical capacitors in the form of round or flat turns or multilayer capacitor chips. The latter are of the type in which the dielectric layers are stacked alternately with metal layers, alternate metal layers extending to opposite sides of the chip, and in which the opposite end faces of the chip are metallized and connected to leads (wires). The leads in all these components are directed radially away from the components (radial wiring) so that they can be accommodated in a cup-shaped housing having in particular a rectangular cross-section. Other circuit elements are, for example, ceramic capacitors, electrical resistors, coils and semiconductor components.
In components as mentioned above in which the circuit elements are incorporated in a housing (mostly formed from an electrically insulating material like a synthetic resin), it must be ensured that the leads are positioned symmetrically with respect to an axial and radial center line. Deviations from this position are at the expense of the required assembly space on a printed circuit board. Since the leads of, for example, a foil capacitor are welded to the end faces of the capacitor cell, both the cell length and the depth of penetration of the wires contribute to tolerances of the spacing between the wires in the longitudinal direction. The wire position with respect to the thickness of the cell is determined by geometrical welding tolerances. Moreover, the thickness of the capacitor cells varies as a function of their capacitance value. This means that in practice it is difficult to position the leads of a cell symmetrically with respect to the cell. Even if this should be successful, one would also have to succeed during assembly to position the leads symmetrically with respect to the circumference of the housing. Generally, assembly takes place by embedding the circuit element in question in a moulding mass, for example an epoxy resin, and then letting the moulding mass cure to secure the element to the housing. Since the moulding mass, prior to and during curing, traverses a low viscosity phase, the possibility exists that the circuit element, if it is not fixed in the housing, changes its position in the housing before the moulding mass has solidified. For example, the circuit element may start floating in the moulding mass or may assume an oblique position under the influence of transport accelerations. If this happens, the leads are not arranged symmetrically with respect to the two pairs of opposite walls of the housing. As already said, deviations from this arrangement are at the expense of the required assembly space on a printed circuit board.
In order to tackle the above problems, two courses have so far been adopted.
1. The circuit element is centered with respect to the housing. The disadvantage of this is that tolerances of the location of the wires with respect to the cell are found again in the location of the wires with respect to the housing (see, for example, DGM 1 911 606). PA0 2. The wires are centered with respect to the housing. So far known solutions of this type have the disadvantage that adaptation of the wire configuration is necessary to make the positioning device at the housing accessible, while as a result of tolerances undefined space remains (see, for example, DE-OS No. 2 048 454.)